1. Field of the Invention
The present invention relates to a torque wrench for measuring a tightening torque of a tightening tool such as a latchet by using a distortion sensor.
2. Description of the Related Art
In conventional torque wrenches, there is one in which a tightening tool such as a ratchet is fixed to the wrench main body, and a tightening torque is computed based on an output of a distortion sensor mounted on a handle part of the wrench main body, having a function that when the computation result reaches a tightening torque set value which has been set beforehand, an alarm or the like is generated, whereby an appropriate tightening torque can be obtained securely (see, for example, Japanese Patent Application Laid-open No. 62-176777).
However, in the case of the conventional example described above, a manufacturer is required to provide plural kinds of torque wrenches having different ranges of tightening torques, but if their effective lengths differ corresponding to the ranges of the tightening torques, main components such as a wrench body cannot be used in common. This causes a problem that it is difficult to reduce the production cost.